At present, when arrested, Police use a statement that includes the words "You do not have to say anything. But it may harm your defence if you do not mention when questioned something which you later rely on in Court. Anything you do say may be given in evidence" (or very similar).
This is a prejudiced statement and should be altered in two respects (the amendments are underlined):
So, in summary, the full statement should read (and be supported by the requisite legislative instruments):
"You do not have to say anything. But it may harm your defence if you do not mention, when questioned, something which you later rely on in Court. Similarly, we undertake to inform you of evidence we have in our possession. Anything you do say may be given as evidence in prosecution or defence".
Point 1.
At present, the statement states that the individual must mention all facts in their defence on initial questioning but places no obligation on the state to reveal facts they already have in their possession and may use in prosecution. This is therefore an immediately biased position against the individual because, subsequently, the state may admit evidence, previously withheld from the defendant, and still have it taken at full value by the court. However, the individual, if admitting evidence after initial questioning, is at a disadvantage by having their defence "harmed".
The pressure of arrest and police questioning may cause people to forget, get confused memories, reveal information that is not relevant but can be used by the state to support the case.
Point 2
The current modus operandi is that if a person states "I am guilty" while under caution, this is used as an admission of guilt and thus undermines their case. However, if a person states "I am innocent", this is not held by the courts with the same importance/value. In other words, the word "evidence", as used in the police statement, is always designed to represent the prosecution evidence not the defence evidence. This point should be clarified with a new statement making the assertion that any mention of facts made by be used by either party in the case for these reasons:
It is important these changes are made to protect the innocent who are arrested. It may also reduce the number of occasions when people opt to remain silent because the law will support that the evidence taken is equally balanced and maybe used for either case.